1. Field of the Invention
The present invention relates to a manually operable sweeping-type printing apparatus for printing data on a recording medium while being manually moved across the medium.
2. Description of the Related Art
A manually operable sweeping-type printing apparatus is disclosed in U.S. Pat. No. 3,767,020 issued to Rowe on Oct. 23, 1973, entitled "Manually Positionable Automatic Printer." This printer comprises a hand-held housing and other components located within the housing, such as a print head, a roll of ink ribbon, a roller, an encoder, and a ribbon take-up shaft. The roller rotates, while being held in contact with a recording medium, as the housing is swept across the medium to print data on the medium. The encoder detects the rotation of the roller, thereby to determine the distance the housing has moved over the recording medium.
As the housing is moved over the recording medium, with the roller kept in contact with the medium, the roller rotates. The encoder detects the rotation of the roller, and outputs a pulse every time the roller rotates by a predetermined angle. The pulse signal output by the encoder and consisting of such pulses, therefore, represents the distance the housing has been swept across the recording medium. In synchronism with these pulses, the print head is driven to print data on the medium, by using the ink ribbon.
Such a printing apparatus must satisfy three essential requirements. First, it must be small enough that it can be comfortably held by any user. Secondly, it must be able to print data of a high print quality, regardless of the level of skill of the operator. Thirdly, it must be easy to manufacture.